The Gallup poll found that when asked about a race between McCain and Obama, and a race between McCain and Clinton, the two candidates are within 2 percentage points.

The poll of 4,355 registered voters was conducted between March 8 and March 12. The margin of error is plus or minus 2 percentage points.

On the Democratic race, the latest Gallup Poll Daily tracking poll found that 48 percent of national Democratic voters favored Obama to be the party's nominee, compared with 46 percent who said the same thing about Clinton.

The poll of Democrats was based on a survey conducted March 10 to March 12 among 1,245 Democratic and Democratic-leaning voters. The margin of sampling error is plus or minus 3 percentage points.